Laser materials processing as known in the art and used herein refers to performance of materials processes, such as cutting, welding, drilling and soldering, using a continuous wave or pulsed laser beam. The average power of such a laser beam may range from as little as approximately one watt to 100's of watts, the specific power being selected on the basis of the particular processing being performed. It is also known in the art to transmit the laser beam from the laser source to the vicinity of the workpiece by means of an optical fiber. Apparatus and method for injecting a power laser beam into an optical fiber for transmission therethrough are disclosed in commonly assigned U.S. Pat. Nos. 4,564,736; 4,676,586; and 4,681,396 respectively entitled "Industrial Hand Held Laser Tool and Laser System", "Apparatus and Method for Performing Laser Material Processing Through a Fiber Optic", and "High Power Laser Energy Delivery System", the specifications of those patents being incorporated in their entirety herein by reference.
As disclosed in the above incorporated patents, injection of the laser beam into a fiber injection end is accomplished by focusing the beam, by means of one or more lenses, onto the prepared input end of the fiber. Specific requirements for the size of the focused beam cone, the beam spot size as focused on the fiber end, and the fiber end preparation are described in the above-identified patents. Compliance with these requirements is necessary in order to successfully inject the laser beam into the optical fiber for transmission therethrough. Implicit in these requirements is the need to properly align the focused laser beam with the fiber end. Misalignment of the beam and fiber end will result in either inefficient or no beam transmission through the fiber. Further, where the laser beam has sufficient power, misalignment will result in damage to the fiber end thereby requiring replacement of the fiber or repair of the fiber end.
Various techniques are known in the art for aligning optical components, such as the alignment of a single core optical fiber with a focused laser beam. Such optical alignment techniques include the use of cameras, microscopes, low power aligning lasers, infrared viewing of a power laser operated at low, non-damaging power levels or some combination of these techniques. A common characteristic of these optical alignment techniques is that they are time consuming, require performance by a skilled optics technician and are based on a subjective assessment made by that technician. That is, the optics technician uses his/her skill to subjectively judge, based on observation using one of the listed alignment techniques, when the components are aligned. The time consuming aspect of such optical alignment techniques and the need for their practice by a skilled optics technician present a problem in a manufacturing environment where laser materials processing is practiced. While it is acknowledged that the known optical techniques provide accurate alignment, it would be desirable to provide an automated technique analogous to such optical techniques that enables positioning of a fiber.
Further, during a processing operation and in order to increase the transmission efficiency of the optical fiber, the beam alignment with the optical fiber injection end may require adjustment. No known system, however, provides automated, real-time optical fiber injection end beam alignment during an entire materials processing operating cycle. With known systems, optical sensors are disposed adjacent the fiber output end where a beam is emitted. If a decrease in the output beam intensity occurs, the beam alignment at the injection end is checked. This monitoring usually is performed by a skilled optics technician.
If the technician does not respond in a timely manner, the optical fiber may be damaged, thereby requiring a time-consuming and costly repair and/or replacement of the optical fiber. Even if the technician responds in time to prevent damage requiring a shut down, during the time required to realign the beam and optical fiber injection end, the system will be operating at less than optimum efficiency.
It is therefore a principal object of the present invention to provide apparatus and method for automated positioning of an optical fiber for laser beam injection which is not subject to the aforementioned problems and disadvantages.